Tackle daunting machines and dumbbells with this guide--and burn more fat

Lifting weights has some seriously cool benefits: It increases lean muscle mass, which boosts metabolism and helps torch calories and shed stubborn fat. It also improves the quality of your sleep, wards off back pain, and protects you from disease.

Despite all this, many women dodge the dumbbells at the gym—in fact, only 21 percent strength-train two or three times a week. It may be that the rest are misguided, feel intimidated, or are just plain avoiding it!

Well, the excuses end here. We enlisted top trainers to create this easy-to-follow weight-room cheat sheet. The payoff of pumping more iron will be a leaner, sexier you.

1. Have a Plan
When you enter an unfamiliar situation (say, the free-weight zone), your body will naturally freeze for a moment and only your eyes will move, says body-language expert Patti Wood, author of Success Signals: Body Language in Business. It's an obvious physical sign that you're confused. Decide beforehand what you'll do as soon as you go into the room. For example, make a beeline for the dumbbells. But which ones? Lifting too much too soon can hurt your form and put you at risk for injury, but grabbing two-pounders won't get you results. New York City personal trainer Dan Ownes gives a head-to-toe exercise barometer of just-right weights for beginners:

If you're doing...lateral raises
Start with...2.5 to 5 pounds in each hand

If you're doing...biceps curls
Start with...5 to 8 pounds in each hand

The occasional slam of a weight stack is par for the course when you're using resistance equipment like the cable machine or seated leg press, but causing a storm of noise is a classic newbie doh! And it's more than just bad manners. "Lowering the weight without control can result in injury," says Brad Schoenfeld, owner of the Personal Training Center for Women in Scarsdale, New York, and author of Women's Home Workout Bible. "It can also prevent you from getting the tone you're after, because you don't work through the full range of motion." Lower the weights slowly enough that you can perform every rep of the exercise with good form (and less clanking!).

3. Breathe Easy

Even seasoned lifters sometimes forget to breathe during a tough move. But it's counterproductive. "You starve the body of oxygen, which forces your heart to work a lot harder," says certified strength and conditioning specialist Josh Kernen, owner of Bridgetown Physical Therapy & Training Studio in Portland, Oregon. Exhale during the major exertion in each move, and inhale while returning to the starting position.

4. Break a Sweat
Go full-steam, or you might as well go home. A good way to gauge your effort: Monitor how hard you feel like your body is working. It's called your rating of perceived exertion (RPE), and it's usually measured on a scale of one to 10, with one being very little exertion (like lounging in bed) and 10 being the max (running away from an angry dog). To build and tone muscle, aim for an RPE of at least seven or eight during workouts, says Kernen. "Even if you're happy with your tone, you still have to hit six or seven to maintain muscle mass."

5. Think Total Body
Your muffin top may be the only thing that's motivating you to hit the gym, but it's a mistake to attack just your least-favorite assets. "Spot-reducing exercises simply don't work," says Schoenfeld. Full-body workouts torch fat more efficiently because they build more lean muscle mass, which in turn burns more calories per day. And think about it: Wouldn't you rather eradicate all your jiggle?

Circuit
A workout format that incorporates strength exercises, performed with little or no rest between each exercise. One entire round of each move is considered one circuit.

Collar
The safety mechanism, usually round, that you put next to the last weight on a barbell to keep the weight from falling off during a workout.

Contraction
The activation of functioning muscle or muscle fiber.

Types of contractions:
• Concentric: The shortening of muscle fibers during the lifting portion of the exercise (e.g., lifting a dumbbell during a biceps curl).
• Eccentric: The lengthening of muscle fibers during the lowering portion of an exercise (e.g., lowering a dumbbell during a biceps curl).

Grip

A grasp, hold, or control. Usually refers to the placement of your hands on a bar or dumbbell.

Types of grips:

• Neutral grip: Palms facing each other
• Pronated grip: Palms facing down or back. Also called an overhand grip.
• Supinated grip: Palms facing up or forward. Also called a reverse grip or underhand grip.

Superset
Completing an exercise with one main muscle group, followed by another exercise with the opposing muscle group, with little or no rest in between.

Work in
To share gym equipment. Complete a set, let them do a set, and continue alternating until you're finished.